in which the short-hand notation 



(l-l//2)c( 

 ^~c<+p+(l-p)Fi 



has been introduced. For the case of no eccentricity, i.e., A= 0, 

 Equations (15') through (18') reduced to the corresponding stress ex- 

 pressions given previously. Also, in the same convenient notation, the 

 following expression for the total radial load acting on a ring frame per 

 unit circumferential length is obtained: 



Q* = -pb(l-i//2)^l + ^— 1 k (21) 



(+P+(l-p)Fi J 



which corresponds to the case of zero initial axisymmetric eccentricity. 



In the case of a ring- stiffened cylinder under some loading, such as 

 hydrostatic pressure which is of interest in the case here, a portion of the 

 deformed shell between stiffeners will act effectively with each ring frame 

 to resist direct stress and bending moment caused by the interaction 

 between the shell and the frames. A knowledge of this "effective width" 

 is of particular interest in a study of the buckling strength of the ring 

 itself and in the elastic and inelastic general-instability analyses of the 

 entire stiffened cylinder (this problem is considered in a later section). 

 It is also important in calculating the stresses in the frame flanges of 

 innperfectly circular cylindrical shell structures. 



In Reference 8, Pulos and Salerno discuss the many "effective width" 

 formulas developed by earlier investigators, and they present a formal 

 derivation of a new forinula to include the "beam-column" effect. Details 



26 



